龙江与刁江底栖硅藻群落结构及影响因子

Benthic Diatom Assemblages Distribution in Longjiang and Diaojiang Rivers,in Relation to Chemical and Physiographical Factor

为研究龙江和刁江底栖硅藻群落结构特征的主要影响因子,采集龙江和刁江共32个样点的硅藻样本,并记录11项河流相关环境理化指标。经过实验室处理及硅藻种类鉴定,2条江中共发现硅藻33属179种,其中:龙江全流域共鉴定出硅藻30属141种,刁江全流域共鉴定出硅藻24属138种。典范对应分析CCA显示2条河流中的硅藻群落都受到水质因子和地理因子的共同作用,前4排序轴累积解释了物种与环境之间关系的60.5%,其中前2排序轴一共解释了硅藻—环境变量的36%,并且物种分布与环境梯度排序轴的相关系数分别是0.948和0.919,较好地反映硅藻—环境因子之间的关系。测试各个环境变量的条件效应并进行蒙特卡罗置换检验,结果表明:水体的pH值、电导率、总磷、海拔、水温、流速是影响该地区河流硅藻群落结构的显著影响因子。

In order to study the main influencing factors of benthic diatom community structure m Longjiang and Diaojiang rivers, the diatom samples of 32 sites were collected and 11 physicochemical indexes in the Longjiang and Diaojiang rivers were recorded. All were processed in the laboratory and the diatom species were identified using optical microscope. 179 diatom species were found in the two rivers, which belong to 33 genus. Among them, 141 diatom species belonging to 30 genus were found in Longjiang river, and 138 species from 24 genus were identified in Diaojiang river. CCA showed that the diatoms in the two rivers are affected by the interaction of physicoehemical and geographic factors. The first four axis cumulative explained the relationship between species-environment in 60.5 %. The first two ordination axes altogether explained the 36 % of the diatom-environmental variables. The correlation coefficients between the distributions of species and the ordination axis were 0.948 and 0.919. It revealed well the diatom-environmental correlation. The conditional effects of each environment variable were tested and Monte carlo displacement inspection was also completed. It showed that the pH value, conductivity, total phosphorus, altitude, water temperature and flow rate were the main factors affecting the structure of the diatom community in the river area.